Many techniques for franking of mail are known. For individual mailers postage stamps are perhaps the best known, while for larger mailers postage meters, such as are described for example in U.S. Pat. No.: 4,301,507; to: Soderberg et al., are available. For very large mailers the U.S. Postal Service permit mail allows mailings of large batches of mail where each mail piece is substantially the same. Permit mail however, is not suitable for large batches of mixed mail where postage values may differ from piece to piece. Until recently, such mixed mail was produced by large mailers, such as oil companies and credit card companies, using high speed inserter systems to assemble the mail and banks of postage meters preset to various amounts to appropriately meter each mail piece. More recently, the assignee of the subject invention has marketed what is referred as a manifest mail system under the trademark "Postedge". In this system a secure apparatus provides a "manifest" which describes a batch of mail, and which includes the total postage value for that batch, as computed by the secure apparatus from information relating to the batch. In order to authenticate the manifest at least a portion of the information on the manifest is encrypted in a secure manner and also printed on the manifest, whereby the Postal Service can easily authenticate manifest by decrypting the encrypted information and comparing it to the plain text manifest.
To assure the accuracy of the total postage value computed by the secure apparatus the system also causes each mail piece to be printed with plain text indicia corresponding to the postage for that mail piece, as well as additional information such as a batch number, mailer i.d., date and time, which identifies the mail piece as part of a batch corresponding to the manifest. The Postal Service, once it has confirmed that the manifest is authentic, may then compare the description in the manifest with the batch to assure that the manifest was generated using information which accurately described the batch. The Postal Service may then re-determine the postage for a sample of mail pieces selected from the batch and compare the re-determined postage values with the indicia to assure that the total postage value for the batch was based on accurate postage values for each individual mail piece. The manifest then serves as evidence of the correct postage that has, or should be, paid for the batch.
In such manifest systems the description of the batch typically will include the total number of mail pieces for each postage value (or equivalently weight) and class (e.g. 1234 1st class mail pieces at 25 cents, etc.). At least partly because confirming that a batch conforms to such a description requires extensive sampling of the batch Postal Service regulations require that manifest mail be in serial number order to facilitate sampling of the batch.
Another, somewhat similar technique for franking of large, mixed batches of mail is disclosed in co-pending, commonly assigned U.S. application Ser. No.: 134,671; filed: 18 Dec. 1987; to Hunter et al.
Another development in techniques for franking of mail involves the use of non-secure printers, such as computer output dot-matrix printers, to print postage meter indicia. Since such indicia may be easily duplicated by a properly controlled printer, security for such meters is provided by an encrypted indicia technique as described in U.S. Pat. No. 4,641,347; to: Clark et al. (Typically in this technique, information including the postage value and additional information sufficient to identify a mail piece is printed on the mail piece in plain text together with an encrypted corresponding message by the meter using a secure encryption algorithm. The indicia is then authenticated to provide assurance that the indicated amount has been paid by decrypting the encrypted message and comparing the decrypted message to the plain text.
Still another system for manifest mail is disclosed in commonly assigned co-pending U.S. patent application Ser. No. 813,447; filed 26 Dec. 1985, now U.S. Pat. No. 4,780,828. In this system as serialized mail is processed a secure apparatus randomly selects a sampling of serial numbers and generates a manifest including the total postage value for the batch and the selected serial numbers, encrypted using a secure encryption algorithm and the postage value for the corresponding mail pieces. The Postal Service may then verify the total postage by decrypting the selected serial numbers and verifying that the postage value for the corresponding mail pieces is correct.
While the above described techniques are believed to function successfully for their intended purpose, certain problems remain. While meters having electronic stamps would be capable of operating at higher speeds than current meters, they still require that each mail piece be individually franked by the meter, and the requirement for serialization is objectionable to large mailers since a serialized batch of mail may easily be inadvertently scrambled and require a great effort to be reordered.
Accordingly, it is an object of the subject invention to provide a method and apparatus for validating a total value for a batch of items; most preferably for validating the total postage value for a batch of items to be mailed.
It is another object of the subject invention to provide such a method and apparatus where the accuracy of the information used to determine the total value may easily be verified.